submodule: bump libtesla from 0ad2838 to f766e9b

Bumps [libtesla](https://github.com/WerWolv/libtesla) from `0ad2838` to `f766e9b`.
- [Release notes](https://github.com/WerWolv/libtesla/releases)
- [Commits](WerWolv/libtesla@0ad2838...f766e9b)

---
updated-dependencies:
- dependency-name: libtesla
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>